Which nerve type carries both motor and sensory nerve fibers and is present only in the spinal nerves?

• A. Sensory nerves
• B. Mixed nerves
• C. Motor nerves
• D. Autonomic nerves

Answer: (B)

The concept here is nerve fiber content. A mixed nerve contains both afferent (sensory) and efferent (motor) fibers, so it can carry impulses to the body and back to the brain. Spinal nerves are formed by the union of dorsal roots (which bring in sensory signals) and ventral roots (which carry motor signals), giving each spinal nerve both types of fibers. That’s why mixed nerves best fit the description. Pure sensory nerves carry only sensory signals, pure motor nerves carry only motor signals, and autonomic nerves are part of the autonomic system with their own specific roles, not the typical mixed category. So the nerve type that has both motor and sensory fibers and is found in the spinal nerves is the mixed nerve.